Sadly, traumatic events, such as this week's airplane crash into a Melbourne shopping centre, are extremely common.

This does not diminish the anguish and grief experienced for individuals involved. It is important to ensure that people remain psychologically healthy in the event aftermath.

While emotional reactions by some people can be expected initially, this distress tends to fade away. However, individuals differ in how severely they are affected by a trauma, and some go on to develop problematic psychological symptoms.

According to the Australian Psychological Society, 4.4 per cent of Australians experience Post-Traumatic Stress Disorder (PTSD) a year, equivalent to about one million people. People diagnosed with PTSD develop severe and intense responses after experiencing, witnessing or being indirectly exposed to an extreme or life threatening event.

The symptoms of PTSD fall into four broad classes: intrusions, avoidance, negative thoughts/feelings and hyperarousal. Intrusion symptoms include frequent re-experiencing of the event through flashbacks and nightmares. Avoidance symptoms involve persistent avoidance of stimuli, thoughts or feelings associated with the trauma. It is these memory-related symptoms, such as flashbacks and avoiding reminders that distinguish PTSD from other psychological conditions, such as depression and anxiety. Hyperarousal symptoms can include increased physiological response such as being startled easily, extreme anger, or difficulty sleeping. Negative thoughts and feelings include difficulty remembering the trauma, low mood and isolation.

People who feel this way after a trauma may develop misconceptions related to the event. For example, people may perceive the world to be overly dangerous and respond by avoiding outside environments. This is can be very disabling and problematic because it leaves few opportunities for these people to correct their flawed belief.

Another unhelpful belief that can arise from trauma is that of seeing oneself as incompetent: if a person feels unable to deal with future bad events, or to control their symptoms, this may lead to further distress and a compounding of their symptoms. If these behaviours can be recognised and addressed early, PTSD may be prevented. For example, if instead the person showing PTSD symptoms can begin to interpret the traumatic event as a unique experience that does not have broader implications or effect their ability to cope with it, they may find it easier to move on.

Most people do not develop PTSD. Research suggests factors such as minority status, female gender and lower levels of education are related to higher rates of PTSD following a trauma. An important factor that can protect people against developing PTSD is having good quality social support immediately following a trauma.

An important factor that can protect people against developing PTSD is having good quality social support immediately following a trauma.

Dr Lauren Monds, University of Sydney

There are other potential responses alongside extreme distress – depression, heavy substance use, and survivor's guilt. It is also possible to respond to such an event with a resignation that such events are not rare or unheard of, and therefore people choose to disengage from all negative information. While this may be a potentially effective coping mechanism in the short term to get through a day of bad news, what does this do to us in the long term? Do we really want to become callous to the human experience?

When a person's distress reaction becomes so severe and impairs their life, professional help may be necessary. Importantly, effective support and treatments are available for people experiencing a variety of reactions to distressing events. Psychological first aid is often employed very early on after a traumatic event, and later on if trauma symptoms remain (symptoms need to have persisted for a month for PTSD to be diagnosed) other methods such as cognitive behaviour therapy with exposure or medication may be useful. For many mental illnesses, there is a considerable gap between the time symptoms were first experienced and when help is sought. That potentially means a long time of suffering in between.

We should also spare a thought for those who regularly witness traumatic events – emergency services personnel. First responders are thought to be at much greater risk of developing PTSD than the general population. These people deserve our support while they work tirelessly to try and save our families and friends.

Dr Lauren Monds is a Research Fellow at the Sydney Medical School and an Honorary Associate in the School of Psychology. This Op-Ed was featured in yesterday's Sydney Morning Herald.